Abstracts

Rationale: Idiopathic generalized epilepsy (IGE) usually presents in childhood or adolescence. New onset generalized epilepsy in mid or late adulthood should raise concern for secondary causes, e.g. mitochondrial disorder, though a substantial minority of ‘truly’ idiopathic patients present after the age of 20 (Marini C, et. al., 2003. JNNP 74:192-196). Sleep disorders may worsen seizures in IGE, but are not recognized to precipitate them. Methods: Two cases of IGE presenting after the age of 30 in the context of an organic sleep disorder. Results: Case I: A 47 year-old male power station supervisor had a cluster of generalized motor seizures over 24 hours. Emergency brain MRI was normal. EEG showed frequent large amplitude bursts of generalized spike-wave activity; hyperventilation and photic stimulation were uneventful. He was treated with valproic acid, and later, topiramate. Further investigation in the community established a diagnosis of obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) was prescribed. The patient was seen in the epilepsy clinic nine months after his seizure cluster for prognostication and due to ‘persisting abnormalities’ on his EEG. There was no previous history of seizures; sleep history confirmed excessive daytime sleepiness and unrefreshing sleep for many years. Physical exam and repeat MRI brain were normal. Interictal EEG on video telemetry confirmed interictal fast (3-4 Hz) generalized spike-wave activity in wakefulness with spike fragmentation and sleep. No seizures were recorded. Repeat polysomnography indicated poorly controlled OSA despite CPAP. Subsequent management has consisted of intensive titration of CPAP pressures and optimization of anticonvulsant dosing. He has had no further seizures, and lately reports improvement in his sleep quality. Case II: A 33 year-old male policeman was seen in the epilepsy clinic with three generalized motor seizures within a three-week period. He also described ‘insomnia’ since early adulthood, with periods during the year lasting up to a month each, of complete inability to sleep for up to 96 hours despite exhaustion. Prior to each seizure, he had virtually no sleep for the previous 48 hours and had drunk a substantial amount of alcohol. Physical exam and cranial CT were normal. Outpatient EEG demonstrated generalized fast spike and polyspikes during photic stimulation at 10-12 Hz, during which he reported feelings of an impending seizure. Logistical reasons have precluded MRI brain and polysomnography. Anticonvulsant treatment with valproic acid has been advised. Conclusions: Patients with late onset (>20 years) seizures are recognized within the IGE spectrum. Pathogenesis of IGE in this age group is thought to be similar to IGE of earlier onset: genetic predisposition triggered by acquired epileptogenic factors. Our two cases highlight the importance of sleep comorbidity in precipitating seizures in subjects with a generalized epilepsy tendency. A thorough sleep history is advised in patients who present with an apparent IGE in later life.